Speed up call frame leaving by grouping refcounted CVs

[ndossche]

Leaving the call frame must destroy all the CVs.
It loops over all the vars and then uses i_zval_ptr_dtor on them. We can skip the non-refcounted CVs in bulk to speed up that loop.

[github-actions]

AWS x86_64 (c6id.metal)

Attribute	Value
Environment	aws
Instance type	c6id.metal
Architecture	x86_64
CPU	Intel(R) Xeon(R) Platinum 8375C CPU @ 2.90GHz, 64 cores @ 2900 MHz
CPU settings	disabled deeper C-states, disabled turbo boost, disabled hyper-threading
RAM	251 GB
Kernel	6.18.38-76.139.amzn2023.x86_64
OS	Amazon Linux 2023.12.20260727
GCC	14.2.1
Time	2026-08-24 19:48:32 UTC
Job details	https://github.com/php/php-src/actions/runs/32770249284 (Artifacts)
Changeset	https://github.com/php/php-src/compare/c96900ee74..bf8433c825

Laravel 12.11.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@c96900e	0.36978	0.37158	0.00032	0.09%	0.37028	0.00%	0.37028	0.00%	1.213	0.000	1.000	25.67 MB
PHP - baseline@c96900e (JIT)	0.34850	0.34976	0.00028	0.08%	0.34908	-5.73%	0.34905	-5.73%	0.349	8.614	0.000	25.78 MB
PHP - sort-cv	0.36890	0.36989	0.00023	0.06%	0.36932	-0.26%	0.36933	-0.26%	0.485	8.552	0.000	25.87 MB

Symfony 2.8.0 demo app - 50 iterations, 50 warmups, 100 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@c96900e	0.66739	0.67055	0.00053	0.08%	0.66812	0.00%	0.66800	0.00%	2.175	0.000	1.000	25.79 MB
PHP - baseline@c96900e (JIT)	0.63982	0.64129	0.00037	0.06%	0.64043	-4.14%	0.64032	-4.14%	0.915	8.614	0.000	26.30 MB
PHP - sort-cv	0.66552	0.67246	0.00113	0.17%	0.66631	-0.27%	0.66596	-0.31%	3.793	7.463	0.000	26.19 MB

Wordpress 6.9 main page - 50 iterations, 20 warmups, 20 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@c96900e	0.58683	0.59033	0.00074	0.13%	0.58793	0.00%	0.58794	0.00%	0.844	0.000	1.000	26.35 MB
PHP - baseline@c96900e (JIT)	0.51509	0.51948	0.00088	0.17%	0.51631	-12.18%	0.51612	-12.22%	2.079	8.614	0.000	26.42 MB
PHP - sort-cv	0.58704	0.59341	0.00128	0.22%	0.58849	0.09%	0.58810	0.03%	1.979	-2.223	0.026	26.31 MB

bench.php - 50 iterations, 20 warmups, 2 requests (sec)

PHP	Min	Max	Std dev	Rel std dev %	Mean	Mean diff %	Median	Median diff %	Skewness	Z-stat	P-value	Memory
PHP - baseline@c96900e	0.45043	0.45332	0.00065	0.14%	0.45198	0.00%	0.45200	0.00%	-0.269	0.000	1.000	26.35 MB
PHP - baseline@c96900e (JIT)	0.14408	0.14503	0.00017	0.12%	0.14454	-68.02%	0.14453	-68.03%	-0.040	8.614	0.000	26.42 MB
PHP - sort-cv	0.45047	0.45409	0.00070	0.16%	0.45179	-0.04%	0.45171	-0.06%	0.717	1.854	0.064	26.31 MB